In the control of internal combustion engines, the conventional practice utilizes electronic control units having volatile and non-volatile memory, input and output driver circuitry, and a processor capable of executing a stored instruction set, to control the various functions of the engine and its associated systems. A particular electronic control unit communicates with numerous sensors, actuators, and other electronic control units to control various functions, which may include various aspects of fuel delivery, transmission control, turbocharger control, or many others.
A turbocharger consists of a turbine and a compressor. The pressure of the engine exhaust gases causes the turbine to spin. The turbine drives the compressor, which is typically mounted on the same shaft. The spinning compressor creates turbo boost pressure which develops increased power during combustion. A wastegate at the turbine intake limits the amount of boost pressure to protect the turbocharger and engine components. When boost pressure reaches a predetermined value, the wastegate opens to provide a bypass for a portion of the exhaust gases which pass directly into the exhaust manifold.
Wastegates may include a mechanical valve or a solenoid actuated valve. In either case, failure of the valve may result in damage to the turbocharger or the engine. Valve failure may occur due to tampering in an attempt to achieve higher boost pressures. Wastegate failure due to tampering may result in turbo overspeed or turbo overboost which may cause excessive wear and damage to the turbocharger and engine components. Of course, other factors may also cause undesired turbo overspeed or turbo overboost regardless of whether the system utilizes single turbocharging or sequential turbocharging in which a plurality of turbochargers are arranged in sequence and selectively operated as desired.